digraph D {

  viwib [shape=diamond]
  mikrotik [shape=box]
  kraftwerk [shape=circle]

  viwib -> mikrotik [style=dashed, color=grey]
  viwib -> mikrotik [color="black:invis:black"]
  mikrotik -> kraftwerk [penwidth=5, arrowhead=none]

}

digraph G {
 viwib -> mikrotik [ label="WAN to eth1"];
 viwib -> mikrotik [ label="LAN to eth2"];
 mikrotik ->kraftwerk [ label="sfp-uplink" ];
}

strict digraph {
                 graph [ bgcolor=lightgray, resolution=128, fontname=Arial, fontcolor=blue, 
                         fontsize=12 ];
                 node [ fontname=Arial, fontcolor=blue, fontsize=11];
                 edge [ fontname=Helvetica, fontcolor=red, fontsize=10 ];

                }